In many data networks, a call between two parties (e.g., a data call) must traverse both local and private networks. For example, a device registered on a Wi-Fi network may attempt to place a Voice Over Internet Protocol (VOIP) call to a device registered on a data network operated by a wireless provider (e.g., Verizon, AT&T, and the like). However, typically the Wi-Fi network and the data network are not directly connected. Instead, the VOIP call usually traverses a packet-switched network disposed between the Wi-Fi network and the data network. For example, the VOIP call may traverse at least one of the Internet, a long-distance router, an IP router, a public or private network backbone, and/or other network entities for connecting disparate wireless networks.
In order to control access to these intermediate packet-switched networks, most network operators deploy a plurality of Session Border Controller (SBCs). The SBCs may ensure that a party attempting to establish a call through the packet-switched network is authorized to access the network. Additionally, the SBCs may facilitate the establishment, management, and/or monitoring of calls as they enter/exit the packet-switched network.
A SBC may also ensure proper routing of packet data addressed to a particular device. To this end, when a device registers on a local network, the local network assigns the device an IP address. The SBC may then associate each call with the IP addresses assigned to each device participating in the call, as well as with a port number and/or a call ID identifying the corresponding call. During a conventional VOIP call, the packet-switched network typically determines the IP address and port number to which packet data should be addressed. As packet data leaves the packet-switched network, the SBC routes the packet data to this determined IP address and port number. Said another way, a conventional SBC acts as a pass-through entity. However, a device on an active call VOIP call may connect to a different local network. As a result, the new local network may assign the device a new IP address.